Three horses have died or were euthanatized following infection with equine herpesvirus type-1 (EHV-1) at a boarding facility in Tioga County, N.Y. The first case was detected about two weeks ago, said officials at the New York State Department of Agriculture & Markets

Clinical signs included fevers, respiratory signs (nasal discharge and increased breathing effort), anorexia (not eating), and neurological problems ranging from weakness and stumbling to an inability to rise. Three of the affected horses to date have died or were euthanatized. Three additional horses appear to have made a full recovery and no others appear to be convalescing. At this time, remaining horses and the facility remain under N.Y. State quarantine.

Diagnostic testing at the Animal Health Diagnostic Center at Cornell University’s College of Veterinary Medicine determined that this outbreak is associated with EHV-1 infection. The virus was isolated from tissues submitted from affected horses that succumbed. In addition, pathologists have determined that microscopic lesions visible in tissues are typical for this infection. The virus can cause respiratory disease, neurologic disease, abortion, and combinations of these problems.

A variety of control measures for EHV-1 are routinely used. In the face of an outbreak, it is important to control movement of horses until 21 days after the last clinical signs are seen in a facility. Routine vaccination of horses will aid in the control of the respiratory and reproductive disease. Vaccines for EHV-1 are not labeled to protect against neurologic form of the disease